In 1900, at the start of the 20th century, motorized land
transportation of people was almost entirely by railroad. The U.S. then
had an extensive steam railroad network of almost 200,000 miles with
about 14,000 miles of electric railways, consisting of both streetcar
and light-rail lines.
[18] In and
around larger cities, many people rode on electric railways but for
long distances they used steam railways (=railroads). Where there
were no railways, travel was usually by animal or human power
(walking and bicycles).

In spite of the inherent efficiency of the low rolling resistance of
the railroad wheel on a rail, the steam engines (locomotives) that
powered steam railroads in 1900 were very inefficient. Only a few
percent of the heat energy of the fuel (coal or oil) was converted to
useful work.
[1] Passenger trains
were also quite
heavy.
Electricity for the electric railways was very inefficiently
generated. It then took about 8 times as much fuel to generate a
kilowatt-hour of electricity as it does today.
[2] Thus, while it may be a surprise to many, rail
transportation in 1900 was relatively energy-inefficient.

Today, most all passenger transportation is by automobile and
aircraft. These are now (2000) over 5 times more fuel-efficient than
the steam and electric railways were in 1900.
[3] Today we get about 32 passenger-miles per gallon (pmpg)
for automobiles (including SUVs). Commercial airlines get the
equivalent of perhaps 38 pmpg
[3]. Note
that 2 persons in a car that gets 20 miles per gallon results in 40
passenger-miles per gallon (40 pmpg). But in 1900, railways only got
about the equivalent of a little over 6 pmpg.
[3]

Yet total passenger fuel consumption has increased roughly 40 times
since 1900. Other things being equal, the fuel consumption should
have gone down by a factor of 5 due to greater efficiency. Why has it
increased so much? Simple, we now travel roughly 200 times as much as
we did in 1900 (by motorized transportation). This is because
population has nearly quadrupled and each person travels about 50
times more miles (4 x 50 = 200).
[4]

In United States for the entire year of 1900, on average, a person
only traveled 210 miles by steam railroad
[ICC-Graph] and perhaps another 130 miles by electric
railways
[6] That sums to 340
miles by rail (nearly a mile per day). Today it's 16,000 miles a
year, mostly by automobile and airplane, roughly a 50-fold increase
over the 340 miles by rail in 1900.
[7]
Why did this happen? It was in part due to the introduction of two
new types of transportation: the automobile and the airplane.

In 1900, there were almost no automobiles. But the automobile had
already been invented, oil fields had been discovered, and oil
refineries built, so the stage was set for the "substitution" of
automobile travel for railway travel. Roads were paved and
automobiles were mass produced so that by the early 1920's there was
more travel by automobile than by railroad.
[BusFacts-1935]. From 1900 to 1920, steam railroad travel
tripled.
[ICC-Graph]. So at first, the
automobile was not just a substitute for railroad travel but a
complement to it. During the 1920's, automobile travel increased by a
factor of 6. Steam railroad travel decreased by about 40% and
electric railway travel decreased by about 20%.
[9]. Thus automobile travel increased roughly 15 times as
fast as the decrease in rail travel.
[BusFacts-1935]

As a result of the replacement of each mile of rail travel by 15 miles
of auto travel, much more fuel was consumed even though the automobile
was then about 3 times more fuel-efficient than the steam railroad
[10] and somewhat more efficient
than the electric railway. This is but one example of where the
introduction of a more fuel-efficient mode, not only failed to
decrease fuel consumption but substantially increased it.

Introduction

How did the improvement in fuel-efficiency (by a factor of 5) happen
in the 20th century? Most of it was due to "replacement" of travel on
an inefficient 1900 rail system by more efficient auto travel. But
some of it was due to significant improvement of the fuel-efficiency
of auto and air transport in the later part of the 20th century.
Ironically, during the 20th century, rail fuel efficiency improved
much more than auto and air. But when that happened, it was generally
too late to be of much benefit since rails had already lost most of
their passenger traffic. Declines in energy-efficiency also happened
at times, only to be followed by rises later on.

Automobiles

Automobile miles per gallon (mpg) started off high in 1900 (25 mpg ?)
since autos were small, had tiny engines and top speeds about the same
as a bicycle. But mpg dropped rapidly during the first decade as
autos became larger and more powerful. As dirt roads became paved,
mpg improved. After 1920, mpg seems to have stayed in the range of
13-15 mpg until federally-mandated fuel economy standards were enacted
in the 1970's. As a result, fuel-efficiency increased from 13 mpg to
21 mpg over the next 25 years (after 1970).
[11]

Trains and Airplanes

In the 1930's air travel was in it's infancy with many times more
travel by train than plane. In the mid 1930's railroads started buying
the newly invented diesel locomotives for use on their fastest
passenger trains. In the mid 1930's railroads started replacing energy
hogging steam locomotives with efficient and streamlined diesels while
airlines acquired the new Douglas DC 3 aircraft to replace poorly
streaming inefficient aircraft such as the Ford Tri-motor.

Airplanes

When jet airplanes replaced propeller planes in the 1950's
fuel-efficiency dropped in half to only about 8 pmpg. Starting in the
1970's, airline fuel-efficiency increased a few times due to improved
engines and a higher percentage of seats occupied.
[13] Since long distance travel by auto gets more mpg than
city driving, and often has more people in the auto, the "intercity"
auto is typically over 35% more fuel-efficient than the airplane is
today.
[14]

Intercity Railroads

Starting in the late 1930's, the steam railroads started to replace
their inefficient steam locomotives with much more efficient diesel
locomotives. In the 1930's, the steam trains only got about the
equivalent of 6 to 7 passenger miles per gallon (pmpg) of gasoline
[10] But the new diesel trains
got about 40 pmpg (6 times better). During World War II (1942-1945)
with gasoline rationing and many trains with all seats full, diesel
trains achieved a whooping 85 pmpg.
[15] Unfortunately, by the time dieselization had been
completed in the mid-1950's railroad travel had declined to only a few
percent of the intercity travel market.
[16]

Just how fuel-efficient is intercity rail today? As compared to 1900,
the higher speeds, air conditioning, and electric heating on Amtrak
trains tend to make them less efficient. Due to the increase in
the fuel-efficiency of the auto after 1970 intercity rail today is
unfortunately not much different than the auto in fuel efficiency.
[17].

Electric Rail Transit (Electric Railways)

This includes streetcars, interurban rail (now called light rail),
and subways. They rapidly increased in energy-efficiency after
1900 due to the increasing efficiency of electricity generation.
From 1900 to 1920, the energy-efficiency doubled, and it nearly
doubled again between 1920 and 1930. After about 1930 their energy
efficiency exceeded that of the auto but the pace of improvement
tapered off. By 1960, the efficiency of power generation had
increased by 85% over 1930
[2] and the
energy-efficiency of electric rail transit was over twice that of the
auto.
[14],
[21] Unfortunately, by 1960, almost all
of the streetcar and interurban lines (about 99%) had been torn up.
[Hilton].

After 1960 there was almost no improvement in electricity generation
efficiency.
[2] The new rail transit and
light rail in the last quarter of the 20th century must be compared
with an auto of increasing fuel efficiency. So today, electric rail
transit is only perhaps about 25% more energy efficient than the
auto-SUV in urban use. See
[25] and
[TEDB]

Buses

Buses were not made until 1921. Before then, automobiles and
modified trucks were used as buses. These likely had better
energy-efficiency than private automobiles since they likely had a
higher percentage of their seats full.

The bus is basically the same technology as the auto but uses less
fuel per seat due to high pressure tires and less wind resistance
(aerodynamic drag). But urban buses waste a lot of energy frequently
stopping for passengers and are much less energy-efficient than
intercity buses (such as Greyhound).

Today, the urban city buses do little better than the automobile in
energy-efficiency, but the intercity buses are the most
energy-efficient mode of travel and get over 125 pass-mi/gallon.
See
[25] and
[TEDB] and
[30]. While intercity buses
have seemingly somewhat improved in energy-efficiency during the 20th
century, urban buses have become significantly worse starting about
1970. Part of the reason may be subsidy, which permits urban buses to
continue operating even when they have few passengers. The intercity
buses are not subsidized and must maintain high passenger loads
(resulting in high energy-efficiency) in order to survive.

Summary

During the early 20th century, the dominant mode changed from
rail to auto. In the 2nd half of the century, air travel became of
major significance. Energy efficiency improved since the new modes
were much more energy-efficient than the old rail mode was in 1900.
Technological improvements (with setbacks at times) also helped. But
ironically, if the auto and airplane hadn't been invented and most all
travel was still by rail, fuel efficiency would have likely increased
even more, since government might have mandated energy-efficiency
standards for rail like they did for autos. And without the
convenience of the auto and the high speed of the airplane, there
would have been far less travel. Thus far less energy would have been
consumed.

So did going from rail to auto and air increase energy-efficiency?
Yes and no, depending on how one looks at it. What is clear is that
the huge increase in travel caused both by these new modes and also by
population growth, resulted in a huge increase in energy consumption.

In the distant past, when land transportation was animal-powered,
it was found that an animal could pull a much heavier cart if the
wheels were placed on wooden rails. This was the first railroad.
Railroad development was of little significance until the practical
railroad steam engine was developed in 1825 in England. [TR p.75-6]
By 1840, the U.S. had a few thousand miles of steam-powered railroads
which exceeded that of the rest of the world combined. By 1860,
railroad mileage had increased by ten fold and the railroad become the
predominant form of motorized land transportation for both passengers
and freight. [TR p.79] Railroad mileage continued to rapidly expand,
reaching a maximum of 250,000 miles in the 1920s. In addition there
were over 30,000 miles of urban electric railroads (including
streetcar lines).
[18]

But the dominance of the railroad was not to endure. Huge amounts of
underground oil were discovered in the late 1800's
[19] and this made automobile (and truck)
transportation feasible. Steam remained king of motorized
transportation for nearly 100 years, not because the automobile (and
truck) couldn't be invented but because there was no cheap liquid fuel
available to run them on.

So prior to steam power, transportation used renewable energy using
sails at sea and plant-eating animals on land. Early railroads burned
wood instead of coal, but the rate of depletion of forest trees became
unsustainable. So in the mid 19th century, railroads were switching
from solar-grown wood to non-renewable coal. See
[20]. The "fuel-efficient" railroads were thus starting us down
the road to an energy-intensive transportation system dependent on
fossil fuels (which in the long run is also unsustainable).

Can we go back to burning wood for land transportation? At the peak
of wood-burning trains in about 1865, rail travel was only about 10%
of what it was in 1900. Thus, while wood could support motorized
travel then, how could it support the travel volume (in
passenger-miles) of today which is about 2000 times greater? While we
could produce power by burning wood with much greater than the 2.5%
efficiency of the railroad locomotives of 1865, by no stretch of the
imagination could we accommodate a 2000 fold increase in travel using
wood as a fuel. See
[20].

The railroad was invented and became widely used mainly because it
took less mechanical energy to move it in an era when the cost of such
mechanical energy was high due to inefficient engines. But it's
difficult to argue that it saved us energy since before railroads,
transportation used wind and animal power.

The automobile was at first much more fuel-efficient than the
railroad. Yet owning an auto resulted in so much more travel that it
didn't save energy either. The magnitude of the energy consumed by
the automobile, dwarfed that formerly consumed by rail travel.

The airplane enabled people to consume the maximum amount of fuel in
the least amount of time. Air travel not only consumed more fuel per
passenger-mile but the consumption per passenger-hour was many times
higher than the auto due to the higher speed.
[13] They enticed people to make very long (and often
unnecessary) trips.

Thus it seems that Neither the railroad, nor the auto, nor the
airplane saved us energy. Instead, they all enticed us to travel more
and thereby consume much more energy.

Some people erroneously think that a major reason for the high fuel
consumption today is because we abandoned rail to opt for the auto and
airplane. In other words, we are using the wrong modes. But if we
continued to travel as much as we do now and did it all by rail, we
wouldn't save much energy either, since the energy efficiency of rail
isn't much better than the auto. In reality, if rail were the only
option for travel today, the volume of travel would sharply decline
due to the inconvenience of schedules and access. This would save a
lot of energy, not because of rail but because of less travel.

If other things are equal, increasing fuel efficiency obviously
saves (conserves) energy. But history shows that the savings due to
increased fuel-efficiency can easily be wiped out by increased
population and travel. The general concept that increased fuel
economy doesn't always save energy due to such other factors is a
very old one, first proposed in 1865.
[26]

There are numerous examples of this concept in transportation. One is
the paving of dirt roads in the 1910's and 1920's which enabled autos
to get more mpg. But a paved road attracts a lot more traffic than a
dirt one. Another is the construction of a freeway so that autos will
get better mpg than they do in stop-and-go driving on city streets.
But the freeways encourage people to live further away from work and
otherwise travel more. Building a rail transit system is yet another
example. It may remove autos from the highways at first, but later,
the resulting lack of congestion on the highways attracts still more
drivers. Between 1970 and 2000, auto-SUV fuel economy increased on
average at 1.5 % per year. If other things were equal, this would
have decreased fuel consumption by 1.5% per year. But instead of a
decrease, fuel consumption increased by 1.5% per year (on average) due
to increased travel. See
TEDB and
[27].

Thus, just increasing energy-efficiency alone may not result in any
energy savings. Conserving energy usually also requires measures
aimed at decreasing travel such as taxes or rationing. See
Travel Less. To do this right is
complex since if people travel less, the resulting money saved (or tax
revenues) may be spent on using more energy in non-transportation
ways.

The crux of the transportation energy problem is that there are just
too many people doing too much travel. The development and
improvements of the motorized modes of transportation have enticed
people into traveling more. The increased travel (and increased
population) in the 20th century not only canceled out the 5-fold gain
in fuel efficiency but increased fuel consumption for travel 40 times.
Thus, in addition to striving to increase fuel efficiency, it's even
more important to strive to reduce the need for travel as well as to
reduce population.